pennantite

pennantite

[′pen·ən‚tīt]
(mineralogy)
Mn9 Al6Si5O20(OH)16 Orange mineral composed of basic manganese aluminum silicate; member of the chlorite group; it is isomorphous with thuringite.
References in periodicals archive ?
Another very interesting mineral at Val Graveglia is goldmanite, a vanadium-bearing garnet found in places in 1988, 1992 and 1996 at the Gambatesa mine, as small (about 1 mm) but perfect green to brown-green dodecahedral crystals associated with manganaxinite, albite, calcite, pennantite, and a vanadium-rich pumpellyite (Palenzona, 1991).
A vanadium-bearing variety of pennantite, the so-called "grovesite" described in 1955 from the Benallt mine in Wales, has been found at the Gambatesa mine in association with manganaxinite, goldmanite, albite and calcite (Palenzona, 1991).